The aim of this research was to determine whether water hyacinth can be used to remove heavy metals, such as cadmium, arsenic, lead, zinc, and copper, from industrial wastewater. Investigations of the pollution removal or prevention potential of aquatic macrophytes, such as heavy metal bio-indicators in aquatic habitats, can prove to be advanced field studies. Water hyacinth is one of the aquatic plant species that has been effectively utilized for the treatment of wastewater. It is extremely effective in removing stains, suspended solids, BOD, organic matter, and heavy metals. This research focused on the use of water hyacinth to treat wastewater from heavy metals. Water hyacinths can grow in sewage, absorbing and digesting contaminants and transforming sewage effluents into comparatively clean water in the process. As a result, the plants have the potential to be used as natural water purification systems at a fraction of the cost of a standard sewage treatment facility. The experiment was performed using healthy, young, and acclimatized water hyacinths. Containment water with a cadmium concentration of 0.5 mg/L, arsenic concentration of 0.5 mg/L, lead concentration of 2 mg/L, zinc concentration of 5 mg/L, and copper concentration of 5 mg/L was added to five different polyethylene pots with 100 g of water hyacinth in each pot. After 30 days, the removal efficiency for heavy metals (Cd, As, Pb, Zn, and Cu) reached 59–92%, and the results were within the permitted limits according to the National Technical Regulation on Industrial Wastewater in Vietnam. Based on this information, it is possible to deduce that water hyacinth can be utilized to remove cadmium, arsenic, lead, zinc, and copper from industrial wastewater effluents efficiently.

Lead (Pb) is a heavy metal that negatively affects human health. Many studies have shown the relationship between lead exposure and various human activities, of which automobile service stations with gasoline emissions are considered the main cause. However, a limited number of studies have specifically considered lead exposure from automobile stations in Vietnam, as well as its impact on human activities and the surrounding natural resources. The objective of this study was to assess the possible risks of lead exposure to the surrounding agricultural and non-agricultural farms of a bus station located in the center of Dalat city, Lamdong province, Vietnam. To address this objective, 45 samples were collected from the soil, irrigated water resources, and vegetable crops of areas both close to and far away from the bus station. These samples were tested using the atomic absorption spectrometry technique. Our findings demonstrated higher lead concentration levels from all three types of samples collected from areas near the bus station. Of which, soil and water samples showed higher than normal exposure values of lead, but these were still under the allowed limits established by the Vietnam standard. Different from the soil and water, vegetable samples surrounding the bus station presented greater lead contamination than the permitted limit. High risk quotient (RQ) indexes were detected to point out that accumulative consumption of leaded vegetables over time could cause lead poisoning and harm human health. This study not only provides significant inferential evidence of the risk of lead exposure to agricultural activities and human health in Vietnam, but also delivers a real-life example for a real-world context.

High‐k materials, such as HfO 2 , Al 2 O 3 , and many others, have been employed to replace the SiO 2 insulator in the gate dielectric device in order to offer significant gate leakage reduction. In this study, the physical properties of hafnium dioxide ( HfO 2 ) thin films were analyzed and characterized in the cases of ‘as‐deposited’ and ‘post‐deposition annealing’ (PDA). Ultra‐thin hafnium dioxide films of thickness 2.5, 5 and 10 nm were deposited on Si (100) substrates using atomic layer deposition (ALD) at temperature of 300° C. After deposition, the films were annealed using furnace in Ar ambient for 10 minutes at 450° C, 550° C, 650° C and 750° C. The thickness, density, roughness and the crystalline evolution of the HfO 2 films were investigated by Grazing Incidence X‐Ray Reflectometry (GIXRR) and Grazing Incidence X‐Ray Diffraction (GIXRD) for both as‐deposited and post‐annealing conditions. Transmission Electron Microscope (TEM) was used to provide image verification of the two‐layer model applied in XRR fitting analysis. Furthermore, the grain sizes were evaluated by X‐ray diffraction peak‐broadening (full width at half maximum, FWHM) calculation according to the Scherrer method. The experimental results showed that the annealing temperatures had significant impact on the thickness, density and roughness of the HfO 2 and SiO 2 layers. In addition, the experimental results demonstrated the grain sizes depend on not only the thickness of the film, but also the annealing temperatures in the crystallization process.

Traditional chicken manure fermentation is mostly natural composting or exposure, which is not only time consuming but also susceptible to weather, resulting in uncontrollable quality and environmental pollution. This research aims to build a smart solar chicken manure fermentation system to control the conditions of chicken manure fermentation effectively, improve quality, and solve the problems of environmental pollution. Hot water produced by solar energy is the heat source for the main system of fermentation, and a backup supplemental heat source by gas heater is applied. The mechanism of drive, agitation, ventilation and drying as well as temperature conditions are controlled by the Arduino’s control core. Fuzzy logic is applied to maintain the optimal temperature, so that the system decomposes the bacteria optimally and reduces the consumed time for fermentation. The chicken manure humidity can be decreased from 70% to 30%, and the effective control system temperature is between 40 and 42 °C, while the pH value is changed from 8.7 to 7.4. The sample analysis of the fermentation also shows that there was 13.12% more organic matter in the chicken manure that added the decomposing bacteria than which did not contain the decomposing bacteria.

A car muffler is a device to improve car noise emission. Some conventional mufflers use layers of glass fiber as a material to absorb noise. However, filling glass fiber is an environmentally unfriendly work, mainly manually filling with chop strand fiber. This research selected a composite material of glass fiber and foam concrete to replace chop strand fiber to avoid this hazard and maintain the muffler’s good noise reduction performance. A response surface methodology with a two-way factorial experimental design repeated the center point twice is performed. The density of the foamed concrete and the weight of the glass fiber is being considered in order to determine the nearly optimal combination of the values in two factors. The response variable is the loudness sensation in Sone of the noise generated from the muffler. At present, the lowest loudness sensation from the two-way factorial design is 16.6494 Sones, which occurred for a muffler with a formula combination of a density of 0.2 g/cm³ and 40 g of glass fiber. The significance of this paper is the presentation of a new application of foam concrete to the green muffler design. To the best of our knowledge, this unique area has never been tackled in the material application of concrete. We have discovered that foam concrete indeed does an excellent job in terms of noise reduction as compared with that of a market muffler.